1. Field of the Invention
The present invention relates generally to a combustion engine start system and more particularly to a pull-cord start system for an engine.
2. Description of Related Art
For many decades small internal combustion engines, such as those used for recreational vehicles and landscaping tools like chain saws, trimmers, tractors, and lawn mowers, have typically used mechanical, manually-operated recoil pull-starters. In a direct recoil pull-starter, an operator of the vehicle or garden tool pulls a cord that is wound about a recoil pulley to rotate the recoil pulley in a first direction. The rotating recoil pulley rotates an engine crankshaft, via a one-way coupling, to start a combustion engine. The one-way coupling allows the crankshaft of the running engine to rotate freely relative to the recoil pulley. When the cord is released by the operator, the recoil pulley automatically reverses rotation, by way of a torsional recoil spring, to retract the cord back around the recoil pulley.
In the past, small engines were designed to start at wide open throttle (WOT) however, current small engines are designed to start at idle. Unfortunately, the end users are accustomed to holding down or depressing the throttle trigger to place the throttle valve in the WOT position even for the idle start engines. Retraining the end user to not hold down the throttle trigger while attempting to start the engine is difficult. In fact, even though new engines are not designed to start with the throttle lever fully depressed, the product of the engine application is returned to the manufacturer because the engine will not easily or reliably start at WOT.
Moreover, when the engine is running and a throttle trigger is fully depressed, ideally, the throttle valve of a carburetor is at WOT. This requires close tolerances that can be expensive to manufacture. If the tolerances are off, the throttle trigger may not be fully depressed when the throttle valve is at WOT and further movement of the trigger can place undue stress upon the linkage components. If the throttle trigger is fully depressed before the throttle valve reaches WOT, the engine will not operate at its full power potential.